Humidification may be carried out by natural humidification, evaporative humidification, supersonic humidification, or the like.
In particular, natural humidification generates a smaller amount of water molecules than supersonic humidification and covers a large humidifying area, thereby providing excellent humidification effects throughout a large area. In addition, the natural humidification consumes lower power than evaporative humidification or supersonic humidification, thereby satisfying requirement for economically friendliness.
Natural humidification is based on a principle that a humidifying medium having a large surface area and many pores absorbs water and provides humidification while being exposed to dry air. Therefore, a corrugated board type humidifying medium is generally used in the art in order to maximize the surface area of the humidifying medium to be exposed to the dry air.
The most important issue of conventional corrugated board type humidifying media is short lifespan due to deposition of inorganic substances therein. Water contains various substances such as calcium (Ca), sodium (Na), magnesium (Mg), various minerals, etc., which are deposited in the form of calcium carbonate and other types of inorganic compounds when water is evaporated from the humidifying medium.
Then, the pores of the humidifying medium are filled with the deposited inorganic compounds and the amount of water to be absorbed by the humidifying medium is decreased, thereby causing reduction in humidification amount below an initial humidification amount over time.
Accordingly, it is necessary for the humidifying medium to be subjected to frequent cleaning in order to maintain high humidification performance. However, even after the humidifying medium is subjected to cleaning, the amount of calcium carbonate or other inorganic compounds removed from the humidifying medium by cleaning is too small to provide significant enhancement of humidification.
To solve this problem, there has been proposed a method of enlarging the pore of the humidifying medium to increase the amount of the deposited inorganic substances to be removed. However, the enlarged pores of the humidifying medium deteriorate capillarity of the humidifying medium, causing difficulty in maintaining proper humidification.